Radio frequency receivers and transceivers are known, including receivers and transceivers that use analog circuits, and receivers and transceivers that use both analog and digital circuits.
Some electronic components used in receivers and transceivers present speed limitations that influence circuit architecture. For example, analog-to-digital converters (ADCs) used in receivers and transceivers can have speed limitations that make it impractical or impossible to convert analog signals to digital signals fast enough to allow operation over a sufficiently wide frequency band for all applications. One such application is in electronic warfare (EW) receivers and transceivers, for which operation is desirable over a very wide frequency range, for example, three Gigahertz (GHz) or more. In order to achieve a frequency range (i.e., a frequency band) of three GHz, an ADC must sample at a rate of somewhat more than six GHz, which ADC is presently not available if the ADC simultaneously needs to have high dynamic range and/or small size and weight.
When a desired bandwidth exceeds the capability of existing electronic components, one approach uses a circuit architecture that provides and operates in separate bands, each having a narrower bandwidth, and then “stitching” the bands together to form one contiguous frequency band having a wider bandwidth.
Stitching of bands presents particular problems for many receivers and transceivers. In particular, separate electronic circuits (i.e., separate band circuits) used to provide the plurality of bands have different characteristics, even if the separate electronic circuits are seemingly identical. For example, particularly at radio frequencies, the separate electronic circuits can generate substantially different amplitudes, substantially different group delays, and substantially different phases. The different characteristics result in undesirable signal distortions upon band stitching, particularly near the intersection of two frequency bands. The distortions can be highly problematic, particularly when a signal, either a narrowband signal or a wideband signal, has one or more frequency components that are at or near the intersection of two adjacent frequency bands.
It would be highly desirable to provide a circuit and technique for which frequency bands of separate electronic band circuits can be stitched together, but for which signal distortions due to band stitching are greatly reduced.